Allylamines reduction

An intramolecular nitrone 1,3-dipolar cycloaddition reaction to give 46 from 45 followed by reductive N-O bond cleavage afforded a stereoselective synthesis of the tetrahydro 177-1-benzazepines 47 the nitrone precursors 44 were prepared in turn by a Claisen rearrangement from an IV-allylamine <06SL2275>. 

In an analogous fashion to the reductive deprotection of allyl alcohols and allyl esters, the deallylation of allylamines is also possible (Eq. 337).270... 

Phosphorylated allenes 195 (R1 = H or Me) are a source of secondary ( )-allylamines. The allenes are treated with an amine R2NH2 (R2 = t-Bu or 4-MeCgH4 and the products, which exist as equilibrium mixtures of enamines 196 and imines 197, are olefinated by successive reaction with methyllithium and an aldehyde R3CHO (R = i-Bu, 4-MeCgH4, PhCH2CH2 etc). Reduction with sodium borohydride finally yields the... 

The overall reaction is best viewed as intramolecular oxidative addition of the C(l)—H bond to the Rh(I) center, causing cyclometalation (25), followed by reductive elimination of an enamine from the Rh(III) intermediate accompanied by allylic transposition. Notably, the allylamine ligand in the initial Rh(I) complex as well as the Rh(III) intermediate has an s-trans conformation with respect to the N—C(l) and C(2)—C(3) bonds, allowing the overall suprafacial 1,3-hydrogen shift to produce the is-configured enamine product. 

Like amides, nitriles can be reduced to amines or alcohols, depending on the reaction conditions. However, catalytic processes are generally superior to the electrosyntheses. The reduction of acrylonitrile to allylamine 557 - 558> is an exception ... 

Much attention has been directed to the possibility that gelsemine is an allylamine. The Emde reduction normally proceeds readily with allylammonium salts, but gelsemine methiodide, with sodium in liquid... 

The reduction of acetylenic Mannich bases exhibits several interesting stereochemical features. The triple bond can be partially hydrogenated with di-isobutyl aluminum hydride, thus giving E-allylamines 293. This reagent provides very good stereoselectivity, the mechanism of which has been investigated. - ... 

The most frequently performed reaction with organometals concerns the well-known addition to the carbonyl group of ketobases. This reaction (Fig. 114) exhibits many affinities with reduction, as it affords an aminoalcohol (296), in this case tertiary, and involves analogous stereochemical features when chiral ketobases are employed. Again, the aminoalcohols produced can be further converted, by dehydration, into allylamines (R R C=CH—CHi—N<), which are useful in pharmaceutical chemistry. - ... 

Reduction of propargylamines. Tertiary propargylamines are reduced by this hydride to (E)-allylamines (equation I). The stereoselectivity is the same as that... 

Catalytic hydrogenation gives a mixture of partially reduced products (enamine and allylamine) and/or saturated amine depending on the conditions used . Partial reduction also occurs on treatment with lithium in ammonia . Dienamines are resistant to reduction by lithium aluminium hydride which therefore provides a means for selective reduction of a less reactive carbonyl group in polyfunctional molecules (Scheme 13). 

Benzene can be separated over cyclohexane with an revalue of 26 with a polvinyl alcohol-poly(allylamine) blend containing a cobalt(II) complex.213 An a-value of 60 has been obtained by pervaporation with a poly(acrylonitrile-co-methyl methacrylate) membrane.214 Membranes of porous polyethylene grafted with glycidyl methacrylate215 and poly(A,A-dimethylacrylamide-co-methyl methacrylate)216 have also been used in this separation with separation factors of 21-22. This is a separation that would be difficult to do by size and by distillation. The two boil only 2°C apart. The cyclohexane produced by the reduction of benzene is the starting material for nylon. The best solution to the problem is to run the reduction to 100% completion. 

The arylation reaction of primary and secondary amines has been investigated using nickel or palladium complexes as catalysts, and bromo- or chloroarenes as arylating agents. Among the complexes tested, the more efficient catalyst is the bis (bipyridyl) nickel (II) bromide, bipy2NiBr2, which affords for example high yields in the arylation of allylamine with /n-bromotrifluoromethylbenzene. The reduction of the haloarene, sometimes observed with the nickel complexes, becomes predominant with palladium catalysts whatever the complex used. 

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